Display screen or portion thereof with an icon



FIG. 1 is a front view of a first embodiment of a display screen or portion thereof with an icon showing my new design; and,

FIG. 2 is a front view of another embodiment of a display screen or portion thereof with an icon showing my new design.

The broken lines represent the bounds of the claimed design and form no part thereof. 

CLAIM The ornamental design for a display screen or portion thereof with an icon, as shown and described. 